This invention relates to a machine for drilling fragile sheet-like materials, in particular sheet glass and the like.
For drilling holes at preset locations on sheet glass, or comparable materials, it is known to use machines having a locating surface cooperating with one or more drill heads, on which the sheet or plate blank can be moved in a two-dimensional fashion as carried on a plurality of small wheels mounted for rotation about their own axes on pivot pins incorporated to said surface.
A sheet or plate blank is located by means of a set of detents arranged to abut against the peripheral edge of the blank; the detents can be registered in position according to the size of the blank and locations of the holes to be drilled. In general, drill heads of the diamond mill type are utilized which are cooled by a continuous stream of water effective to remove the heat generated by the milling action as well as the glass chips being produced.
Such prior machines have some significant disadvantages, first in connection with the positioning of the blank, which must be carried out manually by skilled personnel, and second, in connection with the working condition of such personnel, exposed to an extremely wet environment where cooling water is normally splashed all around.
This working environment also affects the machine life, and in particular its electric motors, since in severe service conditions, such as are imposed by an environment rich in moisture and glass chips, they are apt to be subjected to a faster wear rate and consequent rapid deterioration thereof.
Accordingly, currently available machines cannot be used with processing lines which require a high degree of mechanization of the operations, and where manual intervention must be restricted to checking operations.